The field of nonlinear optics has potential for important applications in optical information processing, telecommunications and integrated optics.
Recently it has been recognized that organic and polymeric materials with large delocalized .pi.-electron systems can exhibit nonlinear optical response, which in many cases is a much larger response than by inorganic substrates.
In addition, the properties of organic and polymeric materials can be varied to optimize other desirable properties, such as mechanical and thermoxidative stability and high laser damage threshold, with preservation of the electronic interactions responsible for nonlinear optical effects.
Thin films of organic or polymeric materials with large second-order nonlinearities in combination with silicon-based electronic circuitry have potential as systems for laser modulation and deflection, information control in optical circuitry, and the like.
Other novel processes occurring through third-order nonlinearity such as degenerate four-wave mixing, whereby real-time processing of optical fields occurs, have potential utility in such diverse fields as optical communications and integrated circuit fabrication.
Of particular importance for conjugated organic systems is the fact that the origin of the nonlinear effects is the polarization of the .pi.-electron cloud as opposed to displacement or rearrangement of nuclear coordinates found in inorganic materials.
U.S. Pat. No. 4,431,263 describes nonlinear optical materials based on polymerized diacetylenes. There is a detailed elaboration of physical and theoretical principles which underlie nonlinear behavior in organic systems. Reference is made to Physical Review A, 20 (No. 3), 1179 (1979) by Garito et al, entitled "Origin of the Nonlinear Second-Order Optical Susceptibilities of Organic Systems".
Other United States patents which describe the synthesis and properties of diacetylenes and polydiacetylene compositions include U.S. Pat. Nos. 2,,855,441; 3,065,283; 3,923,622; 3,994,867; 3,999,946; 4,125,534; 4,195,055; 4,195,058; 4,208,501; 4,215,208; 4,242,440; 4,255,535; 4,328,259; 4,339,951; 4,389,217; 4,439,346; 4,439,514; and prior art cited therein, incorporated herein by reference. British Pat. No. 1,154,191 is of related interest.
Other technical publications which describe diacetylenic properties include Makromol. Chem., 180, 2975 (1979); 182, 965 (1981); 182, 1363 (1981); Mol. Cryst. Liq. Cryst., 93, 239 (1983); 93 247 (1983); 93, 261 (1983); and prior art cited therein, incorporated herein by reference.
Nonlinear optical properties of organic and polymeric materials was the subject of a symposium sponsored by the ACS division of Polymer Chemistry at the 18th meeting of the American Chemical Society, September 1982. Papers presented at the meeting are published in ACS Symposium Series 233, American Chemical Society, Washington, D.C., 1983. Chapters 1 and 8-11 review studies relating to nonlinear optical properties of polydiacetylenes; incorporated herein by reference.
There is continuing research effort to develop new nonlinear optical organic systems for prospective novel phenomena and devices adapted for laser frequency conversion, information control in optical circuitry, light valves and optical switches. The potential utility of organic materials with large second-order and third-order nonlinearities for very high frequency application contrasts with the bandwidth limitations of conventional inorganic electrooptic materials.
Accordingly, it is an object of this invention to provide a novel polymeric composition having an extended conjugated polyunsaturated structure.
It is another object of this invention to provide a thermoplastic polydiacetylenic composition having anisotropic properties.
It is another object of this invention to provide a polydiacetylenic composition which exhibits exceptional nonlinear optical effects.
It is another object of this invention to provide a polymeric nonlinear optical medium which possesses a unique combination of thermoxidative stability and high laser damage threshold.
It is a further object of this invention to provide a novel class of conjugated diacetylenic monomers.
Other objects and advantages of the present invention shall become apparent from the accompanying description and example.